The ALMA correlator, one of the most powerful supercomputers in the world, has now been fully installed and tested at its remote, high altitude site in the Andes of northern Chile. ESO also provided a key part of the correlator: a set of 550 state-of-the-art digital filter circuit boards was designed and built for ESO by the University of Bordeaux in France. With these Tunable Filter Banks, the light which ALMA sees can be split up into 32 times more wavelength ranges than in the initial design, and each of these ranges can be finely tuned.